ImmunIty and dIsease 169What are some applications of immunology?- Vaccination, antibodies, and natural antiviral chemicals have
been harnessed to enhance immunity to specific diseases. - Vaccination (immunization) can stimulate the production of both
effector and memory lymphocytes. - Monoclonal antibodies and cytokines such as interferons are
important tools in medical research, testing, and the treatment
of various diseases.
takE-homE mEssaGEengineered gamma interferon is used to treat hepatitis C,
a chronic, potentially lethal viral disease that impairs liver
functioning. Some kinds of cells produce beta interferon.
This protein has been approved for the treatment of a type
of multiple sclerosis, a disease in which the immune sys-
tem mounts an attack on parts of the nervous system.producing antibodies or memory B cells. While the helpful
effect doesn’t last long, the injected antibodies may counter
the immediate attack.
Vaccines are powerful weapons, but they can fail or have
adverse effects. In rare cases, a vaccine can damage the ner-
vous system or result in chronic immunological problems.
A physician can explain the risks and benefits.
monoclonal antibodies are used
in research and medicine
Commercially prepared monoclonal antibodies harness
antibodies for medical and research uses (Figure 9.16A).
The word monoclonal (meaning “one clone”) refers to the
fact that the antibodies are made by cells cloned from just
a single antibody -producing plasma cell.
At one time laboratory mice were the “factories” for
making monoclonal antibodies. Today most monoclonal
antibodies are produced using genetically altered bacteria.
Genetically engineered plants such as corn also are being
used to make antibodies that may be both cost effective
and safe (few plant pathogens can infect people). The first
“plantibody” to be used on human volunteers prevented
infection by a bacterium that causes tooth decay.
Monoclonal antibodies have become useful tools in
diagnosing health conditions. Because they can recog-
nize and bind to specific antigens, they can detect sub-
stances in the body—a bacterial cell, another antibody, or
a chemical—even if only a tiny amount is present. Uses
include home pregnancy tests (Figure 9.16B) and screening
for prostate cancer and some sexually transmitted dis-
eases. As you’ll read next, monoclonal anti bodies also have
potential uses as “magic bullets” to deliver drugs used to
treat certain forms of cancer.
immunotherapies reinforce defenses
Immunotherapy bolsters defenses against infections and
cancer cells by manipulating the body’s own immune
mechanisms. Cytokines that activate B and T cells are
being used to treat some cancers. Monoclonal antibodies
are another weapon. For example, some aggressive breast
cancers have telltale HER2 proteins at their surface. The
drug Herceptin is a monoclonal antibody that binds to the
proteins and draws a response from NK cells. The drug can
be a double-edged sword, however, because some healthy
body cells also have HER2 proteins, and they are attacked
as well.
Monoclonal antibodies also can be bound to poisons to
make immunotoxins. When these substances bind to an anti-
gen on a cancer cell, they enter the cell and block processes
that allow it to survive and multiply. Several experimental
immunotoxins have been tested against HIV, the virus that
causes AIDS, but to date none has proven reliably effective.
Most body cells that become infected by a virus can make
and secrete antiviral cytokines called interferons. When an
interferon reaches an uninfected cell, it triggers a chemical
attack that prevents the virus from multiplying. Genetically
Figure 9.16 Monoclonal antibodies have a variety of uses
in research and medicine. A In the laboratory monoclonal
antibodies are stored frozen in liquid nitrogen. B The test strips
in home pregnancy tests contain monoclonal antibodies that
will bind to molecules of the hormone HCG (human chorionic
gonadotropin), which is present in urine soon after a woman
becomes pregnant.Simon Fraser/Science SourceAB
© Andrey_Popov/Shutterstock.comCopyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).